The present disclosure relates to a zoom lens and to an imaging apparatus that includes a zoom lens. In particular, the present disclosure relates to a zoom lens that is preferable as an imaging lens system in a digital camera system having an interchangeable lens, and is suitable for shooting of moving image, and relates to an imaging apparatus that includes such a zoom lens.
Recently, a digital camera system having an interchangeable lens has been widely used. In particular, demand has been moved to a so-called mirrorless digital camera that is a digital camera system having an interchangeable lens that includes no quick return mirror in a main body of the camera. For such a camera system, an imaging lens system has been desired that is more compact and has high optical performance. Such a camera system has a function of shooting a moving image. In order to perform automatic focusing during the shooting of a moving image, it is necessary to reduce a weight of a focusing group and to reduce variation in shooting angle of view resulting from the movement of the focusing lens group.
Japanese Unexamined Patent Application Publication No. 2010-271362 proposes a zoom lens system that is configured of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power, that are arranged in order from an object side. In this zoom lens system, a focusing operation is performed through allowing the second lens group to travel along an optical axis. However, in this case, the zoom lens system only has five lens groups that have spacings that are allowed to vary at the time of a zooming operation. Therefore, a traveling amount of each group increases. Accordingly, it is difficult to reduce a size of the zoom lens system. Moreover, a focusing operation is performed through allowing the second lens group as a whole to travel along the optical axis. Therefore, the second lens group has a large weight. Therefore, a driving actuator is increased in size, and also a lens barrel is increased in size. Moreover, when the zoom lens system is driven to perform the focusing operation at the time of shooting a moving image, etc., an issue may also arise that an amount of variation in a range of an angle of view to be shot increases.
Japanese Unexamined Patent Application Publication No. 2011-39560 proposes a zoom lens group that is configured of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having positive refractive power, that are arranged in order from an object side. In this zoom lens system, a focusing operation is performed through allowing the second lens group to travel along an optical axis. However, since the focusing operation is performed through allowing the second lens group as a whole to travel along the optical axis, the second lens group has a large weight. Therefore, a driving actuator is increased in size, and also a lens barrel is increased in size. Moreover, when the zoom lens system is driven to perform the focusing operation at the time of shooting a moving image, etc., an issue may also arise that an amount of variation in a range of an angle of view to be shot increases. Moreover, since all of the six lens groups travel with different loci at the time of the zooming operation, a mechanism that allows the lens groups to travel is complicated, and therefore, the lens barrel is increased in size.